Searching for a better tag than highway=historic

Hi!Please look at this cs discussion: http://www.openstreetmap.org/changeset/50142974I don't like the tag because it a) doesn't give a hint if the road is very old and still usable or maybe not even visible because it was razed centuries agob) is likely to be used by routers, which seems to be unwanted even by the mapper

I assume there are many such roads in the UK, what is the common tagging?